JP3851448B2 - Color adjustment device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color tone adjusting device provided in an image reading apparatus that irradiates light on an image recorded on a film, for example, and reads the image using a line sensor.
[0002]
[Prior art]
Conventionally, an image reading apparatus of this type is known that reads a color image line by line by intermittently transferring a film to be read along a direction perpendicular to the longitudinal direction of a line sensor. That is, while the film is stopped, light output from the light source is irradiated onto the film, and an image of one line is detected by the line sensor facing the light source. After this detection operation, the film is transferred to a predetermined amount by the transfer mechanism. Only transported. Such detection and transfer of images are repeatedly executed, and an image for one screen is read.
[0003]
In such a reading operation by the line sensor, first, an image is pre-scanned at a coarse pitch, and a color image obtained by the pre-scan is displayed on the screen of the display device. The user can adjust the gains related to red (R), green (G), and blue (B) so as to change the color tone according to preference by viewing the color image on the screen. That is, scanning is performed again according to the adjusted gain, and the color image after the color tone adjustment is displayed on the screen.
[0004]
[Problems to be solved by the invention]
In such color tone adjustment, when the pixel data value is saturated, the hue of the reproduced image is changed from the original one. The occurrence of saturation can be recognized by scanning the film after gain adjustment and displaying a reproduced image, but there is a problem that it takes time to determine whether or not the occurrence of saturation occurs. Also, depending on the state of occurrence of saturation, it may not be possible to determine the occurrence of saturation just by looking at the entire image.
[0005]
An object of the present invention is to provide a color tone adjustment device that can immediately determine whether pixel data is saturated due to an adjusted gain when gain adjustment of a color component is performed.
[0006]
[Means for Solving the Problems]
A first color tone adjustment device according to the present invention is a color tone adjustment device that adjusts the hue of a color image composed of pixel data of at least first and second color components, and includes first and second color components. Gain adjusting means for changing the gain, pixel data calculating means for calculating the pixel data of the first and second color components using the gain changed by the gain adjusting means, and the pixel data calculating means. And warning means for outputting a warning indicating that the changed gain is inappropriate when at least part of the pixel data of the first and second color components deviates from a predetermined saturation level. It is a feature.
[0007]
The first and second color components are, for example, one of red, green, and blue, respectively.
[0008]
The saturation level is preferably adjustable. Moreover, it is preferable that the upper limit value and lower limit value of the saturation level can be set independently.
[0009]
A color image may be displayed on the screen of the display device, and a warning may be output as part of the color image displayed on the screen. In this case, it is preferable that a part of the color image is displayed in a color different from the original color.
[0010]
The warning may be output as audio or may be output as a comment on the screen of the display device.
[0011]
The warning unit may be configured to convert pixel data deviating from the saturation level into predetermined pixel data and display a color image on the screen of the display device.
[0012]
The color tone adjusting apparatus of the present invention may further include warning switching means for selectively switching the presence or absence of the warning means.
[0013]
A second color tone adjustment device according to the present invention is a color tone adjustment device that adjusts the hue of a color image composed of pixel data of a plurality of color components, and gain adjustment means that can change the gain of the color component; When pixel data deviating from a predetermined saturation level is included in pixel data of a plurality of color components calculated using the gain changed by the gain adjusting means, a part of the pixel data deviates from the saturation level. And a warning means for outputting a warning indicating the above.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating an image reading apparatus including a color tone adjusting apparatus according to an embodiment of the present invention.
[0015]
In this example, the film M to be read is a negative film, that is, a transparent original, and one color image is recorded on the film M. The film M is intermittently transferred in the direction of arrow A by the document transfer mechanism 10. A light source 20 is disposed above the passage path of the film M, and an imaging lens 31 and a line sensor 30 are disposed below. The light source 20 is turned on and off by a light source drive circuit 41, and the image detection operation by the line sensor 30 is controlled by a line sensor drive circuit 42. The document transport mechanism 10, the light source drive circuit 41, and the line sensor drive circuit 42 operate according to a command signal output from the system control circuit 40.
[0016]
The line sensor 30 has a large number of photodiodes arranged in one row, and each photodiode generates an electrical signal corresponding to the amount of light received. The electric signal read out from the line sensor 30, that is, image data is amplified by the amplifier 43 and converted into a digital signal by the A / D converter 44. The digital image data is subjected to processing such as shading correction in the image processing circuit 45 and then temporarily stored in the memory 46. This image data is read from the memory 46 and subjected to predetermined arithmetic processing such as color correction and gamma correction. The image data is converted into a signal according to a predetermined format by the interface circuit 47 and output to the computer (image processing apparatus) 60 via the input / output terminal 48. The image processing circuit 45 and the interface circuit 47 are controlled by the system control circuit 40.
[0017]
In this embodiment, all operations of the image reading apparatus are controlled by the computer 60. However, the switch 49 is connected to the system control circuit 40, and the operation of the image reading apparatus is controlled by operating the switch 49. You may comprise.
[0018]
FIG. 2 shows the document transport mechanism 10, the light source 20, and the line sensor 30. The film M is supported by a frame body 11, and the frame body 11 is fixed to a plate-like stage 12 by a stopper 13. The stage 12 has an opening (not shown) at a position corresponding to the film M. A rack 14 is formed on the side end surface of the stage 12, and the rack 14 meshes with a pinion 16 provided on the output shaft of the document feed motor 15. The document feed motor 15 is driven based on the control of the system control circuit 40 to control the position of the film M.
[0019]
The light source 20 is positioned above the stage 12 and is configured by periodically arranging light emitting elements 21R, 21G, and 21B that emit blue (B), green (G), and red (R) light in this order. However, this arrangement can be changed according to the purpose. 2 shows only six light emitting elements, more light emitting elements may be provided or fewer. The light emitting elements 21R, 21G, and 21B are supported by an elongated support member 22 that extends in the width direction of the stage 12, and a cylindrical lens 23 that extends in parallel with the support member 22 is disposed between the support member 22 and the stage 12. ing. That is, the light emitted from the light emitting element 21 is condensed by the cylindrical lens 23 and irradiated onto the film M in a line shape.
[0020]
The line sensor 30 is positioned below the light source 20 with the stage 12 interposed therebetween, and is provided in parallel to the light source 20 and the cylindrical lens 23. That is, the line sensor 30 extends in a direction substantially orthogonal to the direction in which the film M is transferred. An imaging lens 31 is provided between the line sensor 30 and the stage 12. The imaging lens 31 extends in parallel with the line sensor 30 and is constituted by a rod lens array. Therefore, when light is irradiated onto the film M by the light source 20, an image recorded on the film M is imaged on the light receiving surface of the line sensor 30 via the imaging lens 31.
[0021]
FIG. 3 is a flowchart showing an image reading routine executed in the image reading apparatus. FIG. 4 shows an example of the screen of the display device of the computer 60. FIG. 5 and FIG. 6 are histograms showing the distribution of the appearance frequency of the pixel values created based on the image data obtained by the coarse scans in steps 102 and 106, respectively. The operation of the image reading apparatus will be described with reference to these drawings. The operation of the image reading apparatus is controlled by clicking a predetermined mark displayed on the screen of the display apparatus using, for example, a mouse.
[0022]
In step 101, it is determined whether or not to start pre-scanning. When the “pre-scan” mark MP on the screen of the display device is clicked, the process proceeds from step 101 to step 102, where coarse scan, that is, exposure measurement is executed. That is, with the light source 20 turned on, the film M is intermittently transferred by the document transfer mechanism 10 at a coarser pitch than the main scan executed in step 111. During this intermittent transfer, the image data for one screen is detected by exposing the line sensor 30 for a fixed exposure time t. In the coarse scan, the light source 20 is controlled so that the light emitting elements 21R, 21G, and 21B are turned on in a predetermined order each time the stage 12 stops.
[0023]
In step 103, a histogram indicating the signal level distribution is created for the R, G, and B image data obtained in step 102. As shown in FIG. 5, an R histogram HR1, a G histogram HG1, A histogram HB1 of B is obtained. In step 104, for each color component R, G, B, a value that is smaller than the maximum value of the histogram by a predetermined amount, that is, the upper effective level DR1, DG1, DB1 is extracted. The upper effective level is a signal level when the cumulative frequency is obtained from the higher signal level in the histogram and the cumulative frequency reaches, for example, 0.5% of the total frequency.
[0024]
In step 105, based on the exposure time t executed in step 102, the upper effective levels DR1, DG1, DB1 obtained in step 104, and a predetermined value (for example, 1023), the optimum exposure time for each color component. Calculated. The optimum exposure time TR for R is TR = (predetermined value / DR1) × t
It is. The optimum exposure time TG for G is TG = (predetermined value / DG1) × t
It is. The optimum exposure time TB for B is TB = (predetermined value / DB1) × t
It is.
[0025]
The second histograms HR2, HG2, and HB2 shown on the right side of FIG. 5 relate to R, G, and B that are expected to be obtained when an image is detected using the optimum exposure times TR, TG, and TB, respectively. It is a histogram. In practice, however, a slightly different histogram is obtained. That is, when the rough scan is executed again using the optimum exposure times TR, TG, and TB in step 106, third histograms HR3, HG3, and HB3 are obtained as shown on the left side of FIG.
[0026]
In step 107, an upper effective level DR2 and a lower effective level dR2 are obtained for the third histogram HR3. The method of obtaining the upper effective level DR2 is the same as that in step 104, and a value smaller than the maximum value of the histogram by a predetermined amount is determined as the upper effective level DR2. The lower effective level dR2 is a value larger by a predetermined amount than the minimum value of the histogram. The histogram HR3 is reversed left and right, and the upper effective level DR2 matches a lower reference value LR1 of a lookup table described later, and the lower effective level dR2 matches an upper reference value LR2 of the lookup table. To be converted. As a result, linear inversion gradation correction is performed, and a fourth histogram HR4 is obtained.
[0027]
Similarly, for the third histogram HG3, the upper effective level DG2 and the lower effective level dG2 are obtained, and the upper effective level DG2 and the lower effective level dG2 are respectively set to the lower reference value LG1 and the upper reference value of the lookup table. Linear inversion gradation correction is performed so as to match LG2, and a fourth histogram HG4 is obtained. Similarly, for the third histogram HB3, the upper effective level DB2 and the lower effective level dB2 are obtained, and the upper effective level DB2 and the lower effective level dB2 are respectively set to the lower reference value LB1 and the upper value of the lookup table. Linear inversion gradation correction is performed so as to match the reference value LB2, and a fourth histogram HB4 is obtained.
[0028]
For the R image, the equation for converting the image data corresponding to the third histogram HR3 into the image data corresponding to the fourth histogram HR4 is:
R normalized data = LR2− (input value−dR2) × (LR2−LR1) / (DR2−dR2) (1)
It becomes. Here, the normalized data is image data corresponding to the fourth histogram HR4, and the input value is image data corresponding to the third histogram HR3. DR2 and (LR2-LR1) / (DR2-dR2) are R color correction parameters.
[0029]
Similarly, for the G image, the equation for converting the image data corresponding to the third histogram HG3 into the image data corresponding to the fourth histogram HG4 is:
G normalized data = LG2− (input value−dG2) × (LG2−LG1) / (DG2−dG2) (2)
It becomes. For the B image, the equation for converting the image data corresponding to the third histogram HB3 into the image data corresponding to the fourth histogram HB4 is:
B normalized data = LB2− (input value−dB2) × (LB2−LB1) / (DB2−dB2) (3)
It becomes. dG2 and (LG2-LG1) / (DG2-dG2) are G color correction parameters, and dB2 and (LB2-LB1) / (DB2-dB2) are B color correction parameters.
[0030]
In this way, in step 107, color correction parameters for determining conversion equations (1) to (3) for performing linear inversion gradation correction are calculated for the R, G, and B image data.
[0031]
In step 108, pre-scanning is performed according to the optimum exposure time obtained in step 105. In the prescan, for example, the end of the film M is set at an initial position facing the light source 20, and images are read at a coarser pitch than the main scan executed in step 111. In this reading, each time the stage 12 stops, the light emitting elements 21R, 21G, and 21B are turned on in a predetermined order, and R, G, and B image data are detected for each line. These image data are subjected to correction processing using color correction parameters, and further subjected to gamma correction by referring to a look-up table (LUT), and then transferred to the computer 60. That is, correction processing is performed on the image data in accordance with equations (1), (2), and (3). The image PI thus obtained is displayed together with other marks on a part of the screen of the display device of the computer 60.
[0032]
In step 109, it is determined whether or not to start the main scan. The operator of this image reading apparatus can determine whether or not to start the main scan by looking at the pre-scan image PI displayed on the screen of the display device. When the “scan” mark MS on the screen of the display device of the computer 60 is clicked, the process proceeds from step 109 to step 111 to perform the main scan. The main scan is basically the same operation as the pre-scan except that the reading pitch by the line sensor 30 is relatively fine. That is, the image data read by the main scan is subjected to correction processing according to the equations (1), (2), and (3), gamma corrected, and then displayed on the screen of the display device of the computer 60. . When the main scan ends, step 109 is executed again.
[0033]
On the other hand, when the “scan” mark MS is not clicked, it is determined in step 110 whether or not to perform the pre-scan again. When the “pre-scan” mark MP is clicked, the process returns to step 107, but when the “pre-scan” mark MP is not clicked, the process returns to step 109. That is, steps 109 and 110 are repeatedly executed while neither mark MS nor MP is clicked.
[0034]
When the “Eject” mark ME on the screen of the display device is clicked in the middle of the image reading routine of FIG. 3, the image reading routine is terminated by interruption processing, and the film M is ejected from the image reading device. Is done.
[0035]
FIG. 7 shows a flowchart of a gain adjustment routine for changing the gains of the R, G, and B color components, and this gain adjustment routine is performed to adjust the hue of the color image displayed on the screen of the display device. The gain adjustment routine is executed in the computer 60, and interrupt processing is performed, for example, every 100 msec.
[0036]
In step 201, it is determined whether the color tone trimming parameter has changed. The tone trimming parameters are changed by moving the gain setting buttons BR, BG, and BB on the screen of the display device shown in FIG. The positions of these buttons BR, BG, and BB are changed by dragging the mouse and moving it left and right. For example, if the R gain setting button BR is displaced to the right of the center, the R gain becomes larger than the value set so far, and the color of the reproduced image becomes reddish. Conversely, if the R gain setting button BR is displaced to the left of the center, the R gain becomes smaller than the value set so far. The same applies to the gains of G and B.
[0037]
If it is determined in step 201 that the color tone trimming parameter has not changed, the gain adjustment routine ends after skipping steps 202 to 209. On the other hand, when it is determined in step 201 that the color tone trimming parameter has changed, gain adjustment is performed in step 202 and subsequent steps.
[0038]
In step 202, the parameter input via the R gain setting button BR is set as the R correction coefficient rK. In step 203, the parameter input via the G gain setting button BG is set as the G correction coefficient gK. In step 204, the parameter input via the B gain setting button BB is set as the B correction coefficient bK. These correction factors rK, gK, and bK have values in the range of −0.5 to 0.5, for example.
[0039]
In steps 205 to 207, gain adjustment is performed for all pixel data constituting one screen. In step 205, the original pixel data of R is multiplied by (1 + rK) to obtain R pixel data after gain adjustment. In step 206, the original pixel data of G is multiplied by (1 + gK) to obtain G pixel data after gain adjustment. In step 207, the original pixel data of B is multiplied by (1 + bK), and the B pixel data after gain adjustment is obtained. Each pixel data after gain adjustment is stored in an image display memory in the computer 60.
[0040]
For example, if the amount of movement of any one of the buttons BR, BG, and BB is too large, the value of the pixel data of that color component is saturated and exceeds the upper limit value, and the color of the reproduced image becomes unnatural. . This embodiment is configured to be able to determine whether or not pixel data is saturated.
[0041]
In step 208, it is determined whether the warning is valid. Whether this warning is valid or not depends on whether the “saturation warning” “ON” mark MN or “OFF” mark MF displayed on the screen of the display device is set to a black circle. That is, when the “ON” mark MN is defined as a black circle, the warning is valid, and when the “OFF” mark MF is defined as a black circle, the warning is invalid. These marks MN and MF are switched between a black circle and a white circle by, for example, clicking the mouse.
[0042]
When the warning is invalid, the routine ends without executing step 209, but when the warning is valid, step 209 is executed. In step 209, the saturation check routine shown in FIG. 8 is executed, and in the image PI displayed on the screen of the display device, pixel data deviating from the saturation level is converted into predetermined pixel data and displayed.
[0043]
In the saturation check routine of FIG. 8, first, at step 301, a parameter N indicating a pixel of one image is set to zero. In step 302, the R, G, and B pixel data are read from the memory for the Nth pixel. These R, G, and B pixel data are Rn, Gn, and Bn, respectively. Here, it is assumed that each pixel data is represented by 8 bits, the upper limit value of the saturation level is 255, and the lower limit value of the saturation level is 0.
[0044]
In step 303, it is determined whether or not the value of the pixel data Rn is equal to or higher than the upper limit value of the saturation level. When the value of the pixel data of Rn is not equal to or higher than the upper limit value of the saturation level, step 304 is executed to determine whether or not the value of the pixel data of Rn is equal to or lower than the lower limit value of the saturation level. When the value of the pixel data of Rn is not less than the upper limit value or less than the lower limit value of the saturation level, Rn = 255−Rn in step 305
The pixel data is inverted by the following equation.
[0045]
Similarly, in step 306, it is determined whether or not the value of Gn pixel data is equal to or higher than the upper limit value of the saturation level. In step 307, whether or not the value of Gn pixel data is equal to or lower than the lower limit value of the saturation level. Is determined. When the value of the pixel data of Gn is not less than the upper limit value or less than the lower limit value of the saturation level, in step 308 Gn = 255−Gn
The pixel data is inverted by the following equation.
[0046]
In step 309, it is determined whether or not the value of the pixel data of Bn is equal to or higher than the upper limit value of the saturation level. In step 310, whether or not the value of the pixel data of Bn is equal to or lower than the lower limit value of the saturation level. Determined. When the value of the pixel data of Bn is not less than the upper limit value or less than the lower limit value of the saturation level, Bn = 255−Bn in step 311
The pixel data is inverted by the following equation.
[0047]
In step 312, 1 is added to the parameter N. In step 313, it is determined whether or not the parameter N is the final value, that is, the total number of pixels of one image. When the parameter N has not reached the final value, the process returns to step 302. However, when the parameter N is equal to or greater than the final value, since the saturation level check has been completed for all the pixels, this routine ends.
[0048]
Based on the pixel data obtained in this way, a color image is displayed on the screen of the display device. That is, in the color image PI displayed on the display device, the saturation component data in the pixel is inverted in the portion PS corresponding to the pixel data exceeding the saturation level. Therefore, the user can easily determine the saturated region.
[0049]
In the present embodiment, when at least a part of the pixel data of the R, G, B color components deviates from the saturation level, not only the color of the saturated portion PS of the image is inverted, but also the buttons BR, BG, A warning indicating that the gain changed by BB is inappropriate is output. This warning is output as a comment PC “! Saturated pixel generation (G)”, for example, on the lower side of the displayed color image PI in the display device, and is output as a sound. In this comment, “(G)” indicates that the G pixel data is saturated.
[0050]
The upper limit value UV of the saturation level when the warning is output is displayed on the screen of the display device, and can be changed using, for example, a mouse. Similarly, the lower limit value LV of the saturation level is also displayed on the screen of the display device and can be changed using a mouse or a keyboard. That is, the saturation level can be adjusted, and the upper limit value UV and the lower limit value LV can be set independently. These are input to the system control circuit 40, and in the saturation check routine shown in FIG. And used as the lower limit.
[0051]
As described above, in the present embodiment, calculation of gain adjustment of R, G, and B color components is performed in the computer 60, and the presence or absence of saturation of the image and pixel data obtained by this calculation is displayed on the display of the computer 60. It is displayed on the screen of the device. Therefore, before the film M is scanned according to the adjusted gain, it is possible to determine whether or not saturation occurs in the reproduced image.
[0052]
Further, in the present embodiment, in the reproduced image after gain adjustment displayed on the screen of the display device, the portion where saturation occurs is displayed in a color different from the original color. It can be easily recognized.
[0053]
【The invention's effect】
As described above, according to the present invention, when the gain adjustment of the color component is performed, it is possible to immediately determine whether or not the pixel data is saturated by the adjusted gain.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an image reading apparatus including a color tone adjusting apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing a document transport mechanism, a light source, and a line sensor when a transparent document is used as a film.
FIG. 3 is a flowchart showing an image reading routine executed in the image reading apparatus.
FIG. 4 is a diagram illustrating an example of a screen of a display device of a computer.
FIG. 5 is a diagram showing a histogram created based on image data obtained by coarse scanning in step 102 of the flowchart of FIG. 3;
6 is a diagram showing a histogram created based on image data obtained by the coarse scan in step 106 of the flowchart of FIG. 3;
FIG. 7 is a flowchart of a gain adjustment routine for changing gains of R, G, and B color components.
FIG. 8 is a flowchart of a saturation check routine.
[Explanation of symbols]
20 Light source 30 Line sensor (optical sensor)
M Film BR R gain setting button BG G gain setting button BB B gain setting button

Claims (10)

A color tone adjusting device that adjusts the hue of a color image composed of pixel data of at least first and second color components,
Gain adjusting means for changing the gains of the first and second color components;
Pixel data calculation means for calculating pixel data of the first and second color components using the gain changed by the gain adjustment means;
When at least part of the pixel data of the first and second color components obtained by the pixel data calculation means deviates from a predetermined saturation level, a warning indicating that the changed gain is inappropriate Warning means for outputting,
The warning means inverts the pixel data deviating from the saturation level, displays the color image on the screen of a display device, and notifies which color component deviates from the saturation level. A color tone adjusting device characterized by the above.   2. The color tone adjustment apparatus according to claim 1, wherein the first and second color components are any one of red, green, and blue, respectively.   The color tone adjusting apparatus according to claim 1, wherein the saturation level is adjustable.   4. The color tone adjusting apparatus according to claim 3, wherein an upper limit value and a lower limit value of the saturation level can be set independently.   The color adjustment apparatus according to claim 1, wherein the color image is displayed on a screen of a display device, and the warning is output as part of the color image displayed on the screen.   The color tone adjusting apparatus according to claim 5, wherein a part of the color image is displayed in a color different from an original color.   The color tone adjustment apparatus according to claim 1, wherein the warning is output as sound.   The color adjustment device according to claim 1, wherein the warning is output as a comment on a screen of a display device.   The color tone adjusting apparatus according to claim 1, further comprising a warning switching unit that selectively switches presence / absence of the operation of the warning unit. A color tone adjustment device that adjusts the hue of a color image composed of pixel data of a plurality of color components,
Gain adjusting means capable of changing the gain of the color component;
When pixel data deviating from a predetermined saturation level is included in the pixel data of the plurality of color components calculated using the gain changed by the gain adjusting means, a part of the pixel data is deviated from the saturation level. A warning means for outputting a warning indicating the departure,
The warning means inverts the pixel data deviating from the saturation level, displays the color image on the screen of a display device, and notifies which color component deviates from the saturation level. A color tone adjusting device characterized by the above.

Images